Police and military officials say two buses have been targeted in bombing attacks in southern Philippines, leaving at least six people injured.
Senior police official Rolen Balquin said on Sunday that improvised explosive devices were used to target the buses near the town of Isulan late on Saturday.
Regional military spokesman, Colonel Prudencio Asto stated that four passengers, a driver, and a conductor were injured during the incident.
The vehicles caught fire and firefighters were called in, he added.
"Initial findings of the explosives and ordnance team revealed that the explosions were caused by an improvised explosive device made out of ammonium nitrate, fuel, and oil with common nails," Asto told reporters.
No one has claimed responsibility for the bombings so far, and no motive has been determined.